GOV-220: Retire deployment docsite sources

[captjt]

Summary

• Removes the legacy docs-site/ ReadMe-style documentation source from the public deployment repository.
• Removes docsite-ci.yaml and the README badge/reference for that legacy docs validation path.
• Updates Helm CI and release package validation to enforce release manifest docs metadata instead of validating copied Markdown docs.
• Extends schemas/release-manifest.schema.json so release manifests can record self-hosted documentation provenance, including sourceRepository, sourceCommit, sourceFormat, and workflowRunUrl.
• Updates release packaging so customer packages include charts, examples, checksums, and the release manifest, but no longer bundle deployment-owned docsite source.

Why

GOV-220 moves public-facing release documentation out of the deployment repository and into eqtylab/governance-platform-docs. Deployment remains the public release artifact repository, but docs are now prepared and validated before sync, then recorded in the release manifest as provenance instead of copied as local docsite source.

This keeps the public deployment repository focused on release artifacts while still preserving a verifiable link to the exact documentation build used for a release.

Validation

• Ran git diff --check.
• Ran jq empty schemas/release-manifest.schema.json.
• Parsed .github/workflows/helm-ci.yaml and .github/workflows/release-platform-package.yaml with Ruby YAML loading. Ruby emitted existing local gem warnings, but both workflow YAML files parsed successfully.

[tmccoy14]

🚀